1. Field of the Invention
The present invention relates to a centrifugal compressor with a vaned diffuser.
2. Description of the Prior Art
Japanese Unexamined Patent Publication No. 57-159998 discloses a centrifugal compressor with its operable range broadened by small rotatable vanes at the inlets of a vaned diffuser. Japanese Unexamined Patent Publication No. 58-124099 discloses another design for broadening the operable range of a centrifugal compressor wherein a vaned diffuser comprises a pair of circular rows of vanes with the inner row of vanes movable in a direction parallel to the rotation axis of the impeller.
However, the centrifugal compressor of the Japanese 57-15998 requires a rather complex and highly accurate mechanism since the compressor must be provided with small rotatable vanes as many as the diffuser stationary vanes. The compressor of the Japanese 58-124099 requires large-sized movable parts in order to provide the parallel-movement mechanism, although the mechanism can be simpler than that of Japanese 57-159998.